One of my little projects is browsing NASA archives of lunar and martian imagery for anomalies.
While browsing some Lunar Orbiter images from here :
ftp://pdsimage2.wr.usgs.gov/pub/pigp.../lunar_orbiter
(these images are in .tif format so you need a .tif viewer that can zoom, like paintshop pro or irfanview)
i suddenly had a thought about the craters.
Apparently the moon is around 5 billion years old, so one would expect heavy cratering, but one would also expect asteroids to hit the moon from all sorts of angles. And yet, practically every single crater (believe me i've spent hundreds of hours looking at these images and seen a lot of craters) leaves a nicely circular impact pattern.
This implies that all of these asteroids have hit the moon perfectly vertically, none have come in from an angle less than or more than 90 degrees to the moon's surface.
Someone must have spotted this before ? Is there a known reason, or is my common-sense at odds with my lack of astronomical knowledge ?
Any input greatly appreciated.
*** EDIT ADD ***
If anyone wants to download these images you are advised to use a proper FTP client like FileZilla :
http://filezilla-project.org/download.php
otherwise you will experience connection problems and slow downloads.